I suggest you do everything in your power to avoid grass, especially freshly cut grass. Avoidance would also include spending as much time as possible in an air-conditioned interior environment. If that doesn’t suffice, you should pose this question to your FP or Obstetrician regarding the most effective, yet safe non-sedating antihistamine. The safety issue must take into account which trimester of your pregnancy will encompass the grass allergy season.